1. Technical Field
The present invention relates to a technique for processing a waveform of an impulse response used to apply reverberation to a sound signal.
2. Background Technique
In a device for applying reverberation to a sound signal by a convolution operation of an impulse response, a technique for changing a reverberation time length (hereinafter, referred to as ‘reverberant time’) during which reverberation is continued has been conventionally proposed. For example, Patent Reference 1 discloses a technique for generating a new impulse response of a desired reverberant time by multiplying impulse responses of two types by an exponential function, respectively, and then adding (linear combining) the multiplied responses. [Patent Reference 1] Japanese Patent Application Publication No. 2004-294712
However, in the technique described in Japanese Patent Application Publication No. 2004-294712 to reduce the reverberant time by multiplying the exponential function and thus reducing the intensity of the impulse response, an amplitude of the impulse response at a rear part (around the rearmost part of the reverberant sound) after processing is excessively reduced. Therefore, a problem in which the reverberant sound lacks volume (even worse, a listener cannot listen) occurs.